Unimolecular mass-analyzed ion kinetic energy spectra of model polychlorinated biphenyls were analyzed with respect to the type of fragmentation which controls the kinetic energy release in the major decompositions of the molecular ion, giving new correlations of structure with spectral fragmentation behavior. Collision-induced decompositions of M plus 1 ions produced in chemical ionization of aliphatic esters and small CnH(2n plus 1)O cation (from collision-induced charge reversal of alkoxide ions) were studied as models for the amount of analytically useful information available by induction of collisions in the mass spectrometer. Collision-induced dissociations lead to additional analytical information from the mass spectra of Di-2-ethylhexylphthalate metabolites.